Description

DROP USER removes the specified user
from the database. It does not remove tables, views, or other
objects owned by the user. If the user owns any database you get
an error.

Use CREATE USER to
add new users, and ALTER
USER to change a user's properties. Postgres comes with a script dropuser which has the same
functionality as this command (in fact, it calls this command)
but can be run from the command shell.